second dog?

Question
My husband and I have a 9 month old black lab. All is going well and she is a well socialised, friendly, bouncy pup. However I popped into the dog trust and saw a wee 4 year old terrier x whos owner had died and totally fell for him. We also have an 8 year old cat who has just got used to the pup. (He hated her initially!) My husband feels that now we have reached a nice harmony, he's frightened we'll upset both current pets. The wee terrier is a placid we guy who looks like he'd be no trouble at all. I really want to rescue him and feel that I could probably talk my husband into it!
Does this second dog thing ever work well and what do you think?

Answer
I think it would be fine if they are introduced carefully.  I also think it's great to rehome a dog ,  and give it a second chance.  :-)

The best way to do it is to let both dogs meet on neutral ground.  Like a park where your dog hasn't been. Have plenty of treats and reward the dogs if all is well.  Your lab will come to see that is is beneficial to her to have the pup around.  

Also maybe have him neutered if the dogs trust don't routinely do it.

All should be fine.  Labs are good natured dogs generally.